Editor’s Note: Nir Eyal  writes about the intersection of psychology, technology, and business atNirAndFar.com . He is the author of the forthcoming book “Hooked: How to Drive Engagement by Creating User Habits ”.

Step 1: Build an app. Step 2: Get users hooked to it. Step 3: Profit. It sounds simple and, given our umbilical ties to cell phones, social media, and email inboxes, it may even sound plausible. Recently, tech entrepreneurs and investors have started to look to psychology for ways to strike it rich by altering user behavior. Perhaps you’ve read essays  on how to create habit-forming technology and figured you’d give it a shot?

Well hold your dogs Pavlov! Though I’m an advocate  for understanding user behavior to build high-engagement products, the reality is that successfully creating long-term habits is exceptionally rare. Changing behavior requires not only an understanding of how to persuade users to act — for example, the first time they land on a webpage — but also necessitates getting them to behave differently for long periods of time, ideally for the rest of their lives.

The good news is that that companies that accomplish this rare feat are the ones associated with game-changing, wildly successful innovation. Google, Apple, Twitter, and Android come to mind. As we enter a world where, according to Paul Graham, everything is becoming more addictive , the companies that successfully form and control habits in the future will come to dominate the industries of tomorrow.

Habits or Hype?

But claiming that habits are the keys to success is a tall order. If people like me provide ready-made formulas and guidebooks on how to create habits , why isn’t every company that alters user behavior succeeding?

Zynga, an enterprise whose business model depends on hooking millions of people to its games, is hemorrhaging users employees  and investors . What makes some habits stick while others die like virtual cows on their way to slaughter?

Turns out that like any discipline, habit design has rules and caveats which explain why some products change lives forever while others create fleeting fads.

Habits are LIFO

New behaviors have a short half-life as our minds tend to revert back to our old ways. Experiments show  that lab animals habituated to new behaviors tend to regress to their first learned behaviors over time.

This helps explain the overwhelming evidence that people rarely change. Research shows that nearly everyone who tries to lose weight gains back the pounds  within 2 years. Two-thirds of alcoholics who enter a rehabilitation program will pick-up the bottle  and their old habits within a year’s time.

Old ways die hard and new habits smother easily. To borrow a term from accounting, behaviors are LIFO — last in, first out. This presents an especially difficult challenge for product designers trying to create businesses based on new behaviors.

Keep ’em Guessing

If long-term habits are so hard to create and new behaviors are the ones most likely to be abandoned, how do product designers stand a chance of becoming part of users’ daily lives? The answer lies in the reason users start using the product in the first place: rewards.

In nature, things are relatively predictable — fire is always hot — so our brains drive us to figure out how things work. Thus, habits are just a way for the brain to improve reaction time by not thinking as much. “Hmm, last time I touched the fire, it hurt. I won’t do that again.” In fact, much of what we do every day is habit, requiring little or no conscious awareness.

We’re fine flying on cognitive autopilot. That is, until we encounter something new. When the unknown threatens our safety, we feel fear. But when we know we’re ok, this temporary uncertainty is experienced as novelty, and our brains can’t get enough of it.

For example, watch a baby’s first encounter with a dog. Not only is it incredibly cute, it is a demonstration of the mental wiring which makes us inherently curious. “What is this hairy monster in my house?” the baby must think. “Will it hurt me? What will it do next?” The child is filled with questions, uncertain if this creature will cause it pain or bring pleasure. When it’s certain the dog isn’t a threat, the baby experiences delight , exploding in a burst of infectious giggles.

Until one day, the kid learns enough about the pup to predict its behavior. Suddenly, the doggy is no longer entertaining and the child’s attention moves on. Now he is occupied with dump trucks, fire engines, bicycles and candy — things that stimulate the senses in new ways. Poor Rover is left all alone.

To keep our attention, products must have a degree of novelty. Withoutvariability , users figure out the patterns and tire of the experience. As Tadhg Kelly wrote  about Zynga users, “Their play brains start to realize that they are seeing the same frames again and again, with the same actions and the same constraints. So [the games] become instantly boring.” Though the Zynga “-Ville” franchise was novel, even addictive at first, once players figured out the larger game mechanics, they moved on.

Machines vs. People

But not all habits have the fleeting life span of FarmVille-style games. In fact, many products do form long-term behaviors. What differentiates World of Warcraft or Facebook — products that retain engaged users for years — from bygone fads like Pac Man or Tamagotchi , which hooked users for a while, but quickly lost their grip?

A distinction can be drawn between rewards that are infinitely variable versus those which have finite variability. Products with finite rewards are built to be experienced the same way. Even an addictive video game always operates under the same rules. Of course, the maker can alter the dynamics of the game, changing aspects of play based on the users’ actions, but the fundamental rules, the mechanics, remain the same.

The game is a constructed system, a machine, and if it is a single-player game , it will be enjoyed, completed, and discarded. Even bestselling books, movies, and music follow the same usage pattern. Once these products are made, they don’t change and become nearly worthless after their mysteries are revealed. Their variability is exhausted when the game is completed, the last page of the book is turned, or the lights come up in the theater.

Nearly all of us have played a slot machine, but ultimately, we figure out the rules and patterns and come to understand that the game is designed to take our money, so we move on. Addicts however, those who form uncontrollable and often detrimental obsessions, are the exception rather than the rule. And while businesses should never try and encourage addiction, the fact is that like slots, technology products with finite variability do not form long-term habits in most users.

However, some products are built to be infinitely variable. These products involve rewards users find novel for long periods of time. For example, few things are more fascinating to people than other people; we always want to know more. Whether communicating with loved-ones or keeping up with celebrity gossip, we love the infinite possibilities endemic to the human experience.

Even World of Warcraft, the legendary multiplayer online role-playing game, is more about collaborating with others than completing the game. Though users can play aspects of the game alone, it requires characters to work together in groups to overcome major challenges. World of Warcraft players spend hours strategizing and socializing, both on and off-line. It’s more than a game; it’s a tribe .

Even a bad experience will not stop people from using products with infinite variability. Early iPhone users cursed AT&T for years, even heckling Steve Jobs on stage to show their displeasure. But few could bear to abandon their “Jesus phones ” because compared to rivals, the iPhone and its accompanying app ecosystem was a panacea of limitless possibilities.

Facebook users revolted multiple times when the company made changes to its interface. But they never left in any significant numbers, helping push the social network to over a billion users. Of course today, Facebook has lost some of its luster as it grapples to control user behaviors migrating to mobile, a massive disruption to its business model.

No Guarantees

No business can ensure customers use its products forever. Our consumption habits today will inevitably be replaced with new behaviors in the future. But it is important to recognize that products, which leverage infinite variability tend to be pushed out by disruptive innovations whereas finite variability business fizzle out by themselves.

Habits do not ensure perpetual users, but short of a disruptive change , they provide an opportunity to form a sustainable competitive advantage. The products that become a facet of users’ everyday lives will remake the web. By understanding the kinds of rewards systems that create long-term habits and the rules of habit design, companies can improve lives  while building lasting businesses.

— Follow Nir on Twitter@nireyal.

Thank you to Maurits Kaptein of Science Rockstars  and Max Ogles  for reading versions of this essay.